1. Field of the Invention
The invention relates generally to the formulation and fabrication of components or elements using photoluminescent materials as the light source.
2. Discussion of Background
Present components or elements using photoluminescence for illumination commonly use either photoluminescent phosphors utilizing 1) zinc sulfide or 2) “alkali earth aluminate” referring to a compound containing aluminum, oxygen, and an alkaline earth metal (exemplary alkali earth aluminates include, for example, strontium aluminate [e.g., SrAl2O4]), or “alkali earth silicate” refers to a compound containing silicon, oxygen and an alkaline earth metal (exemplary alkali earth silicates include, for example strontium silicate) as the photoluminescent phosphor. These phosphors are most often dispersed in a polymer, encasing the photoluminescent phosphors and allowing the phosphors to be exposed to an activation source of light in the visible and ultraviolet spectra. For the purpose of elucidating certain aspects of the different embodiments, the term “alkaline earth metal” refers to an element from Group II of the periodic table. Exemplary alkaline earth metals include, amongst others, beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba) and radium (Ra).
Photoluminescent phosphors are commercially available in a wide range of average particle sizes including smaller than 5 microns, 5 microns to less than 20 microns, 20 microns to less than 50 microns, 50 microns to less than 90 microns, 90 microns to less than 250 microns, 250 microns to less than 1,000 microns, and 1,000 microns and greater. Present materials using photoluminescence for illumination often use photoluminescent phosphors that are not well size-optimized for the particular application for which they are being used nor are the polymers in which they are cast, necessarily optimized in their resin to catalyst mixing ratios to provide the best properties for mixing and casting.
While some specialized photoluminescent phosphors are coated to prevent absorption of luminance performance degrading moisture, most are not. Further, most present manufactured components or elements using photoluminescence for illumination are often hydrophilic, absorbing moisture over time that eventually causes the photoluminescent phosphors to deteriorate and reduce their ability to emit light.